Bromination products of 4, 4&#39;-dimethyl-6, 6&#39;-dichloro-thio-indigo and process of making the same



W517i use as our starting material.

- Patented Sept. 1, 1931 STATE PATENT OFFICE IVAN GUBELMANN, JOSEPH B. OESCH, OF SOUTH MILWAUKEE, AND EMERIG HAVAS, 01 BY MESNE ASSIGNMENTS, T NEWPORT CHEMICAL CORPORATION, A CORPORATION OF DELAWARE r MILWAUKEE, VIISGONSIN, ASSIGNORS,

BnoMmATion rnonuors or 4,4-DIMETHYL-6,6FDICI-ILORO-THIO-INDIGO AND PROCESS 1 or MAKING THE SAME a No Drawing.

n) It is a further object of this invention to provide a method of 'brominating 4:.4J-di' methyl 6.6 dichloro ,'tl1i0 indigo whereby considerable economy in the use of bromine may be efiected'; and whereby varying shades "is of dyestuffs may be produced depending upon the amount of bromine introduced into the molecule. 7

Other and further important objects of this invention will become apparent from the i following description and appended claims.

While there are described in the literature numerous halogenated thio-indigo dyes, none of them, however, are prepared from 4.4- ,dimethyl-6.6-dichloro thio-indigo, which we Our process maybe expressedby the. following chemical equation,fwherein :0 represents an indefinite number of atoms andty represents up totwoatoms;

7 CH3 V 1 o 0 I I We have discovered that-by thecarelul treatment of 4.4-dimethyl-6.6-dichloro-thioindigo with .a brominating agent, there are formed new and valuable vat dyestuffs,vary- CH3 c ing in shade from a yellowish red to a bluish 1 red, according to the, extent to which the bromination is carried. t V

For example, if 4L4 dimethyl 6. 6 di chloro-thio-indigo is dissolved in sulphuric acid monohydrate and treated with bromine,

Application filed June 25,

1927. Serial No. 201,556.

new dyestuffs are obtained varying in chemiproduct equivalent in bromine content to a mixture of 96% of the mono-bromo and 4% of the di-bromo derivatives.

This economical use of bromine is the more surprising in view of the fact that the literature, to the best of our knowledge, fails to describe a halogenation process in connection with indigoid compounds, which gives such high efficiency in the use of bromine.

We have further observed that we can a]- terto a limited extent. the degree of bro-' ination of 4;4c'-dimethyl-6. 6'-dichloro-thioindigo by using a constant amount of the brominating agent and changing the'concentration of the sulphuric acid; For example,

by using 1 atomic weights of bromine and sulphuric acid stronger than monohydrate,

the ratio of dibrominated dye to mon0-bro-- minated dye is higher than when using monohydrate, and the shade of the 'dyestufl is yellowerthan when using monohydrate. This phenomenon of altering the degree of bro:

"sulphuric acid used is probably best explained by the fact that in working with sulphuric acid equal in strength to monohydrate,there is an evolution of sulphur dioxide accompanied by an oxidation of liberated hydrcbromic acid, thereby resulting in the re-formation of additional bromine usually not available for brcmination. I

It is therefor obvious from the above description that our process of bromination may be easily manipulated to produce dyestuffs of this type which contain -bromine-in varying amounts according as theconditionsotthe bromination process are varied.

'lVhi'le' it is ditficult to determine the position of the entering bromine atoms, it isap parent that they may enter into any of the four positions, na1nely,"the5.5" positions or the 7.7 positions.

The bromination pro ducts oi -1.4 -di:methyl- 6J6-dichloro-thio-i ndigo vary as to shade,

de-nendingupon the amount of bromine i-ntroduced into the molecule. They range in shade from-a yellowish red tobluish red, thefproducts containing greater proportions of bromine producing thebluish red shades.

The othergeneral properties of the mixtures are in a large degree similar to the properties of the mono-brominated product, which is herein described in detail. The 111 ono-bro'mo 4.4-dimeth'yl-6.-6-dichloro-thioindigois a dark coloredpowder which is soluble in concentrated sulphuric acid. im-' parting thereto a greenish color, and can be precipitated therefrom by the addition of water, in thefor-m of a red precipitate. The mono -bromo product is sparingly soluble in a-cetic' a cild :or alcohol "with areddish colora 'tion; is spaninglysoluble in boilingbenzene closely in bromine content to the monobromo derivative and constitutes in the dry state, a dark powder yielding by treatment with sodium hydrosulphite, a yellow vat from *which cotton is dyed a reddish tint.

By following the conditions given in the above example but varying the amount of bromine used or the concentration of sulphuric acid employed, or both, various mixtures of brominated 'l/lrlimethyl-GJ6'-dichloro-th'io-indigoes may be produced. In general, concentrated sulphuric acid varying in strength trom B, to ()leum may be employed, the efliciency in the use of the bromine being highenwhen 'thehighe'r acid concentrations are used.

lVeare aware that numerous details of this process may be varied throughout a wide range-without departing from the spirit of this invention, and we therefore do not propose to limit the patentzgranted hereon other avise than as necessitated by the prioriart.

We claim as our invention r 1. .A process for preparing brominated 4E4- dsimethyl-fi;6-dichloro-thio-indigo containing substantially less thantwo bromine atoms tothe molecule, which comprisestreating 4.4- dimethyl 6.6- 'dichloro thio indigo in concentrated sulphuric acid solution with 2:1 brominatin'g agent.

2'. A process forprepa-ring a'brominated l;4:-"dimethyl 6.-6' dichloro-thio-indigo corresponding closely in bromine content to the mono-bromo derivative, which comprises treating 4.4L-dimethyl-6.6-dichloro-thio-in- 'di'go dissolved in concentrated sulphuric acid with a brominating agent.

3. Aiprocess for preparing a brominated jl=.4-dimethyl-6.6'-diehlorothio-i-ndigo corresponding closely in bromine con-tent to the with zvreddish violet "coloration, but is easily Q' Q Tl which Comprises soluble imborHngmaphthax(in n itro-b'enzene s 4A"dlmethvlfi'w'dlchlm'o'thln'm' with edighflglgfl 1 t,i, d a digo dissolved in sulphuric acid monohv- .lowiflfluqrescenca 75th a lkalin d j drate. with substantially one and one-half agents suc-h as sodium hy'dresulph te, it yes :a light yellovv vat from which i'mmordanted cotton *is dyedbluish redsha des.

W'itheut limiting our invention to 'any particular procedure, the following example, in which parts by weight are given, will serve 'to illustrate our method in its preferred form it 50 parts of 4.4-dimethyl-6ifi dibh'lorothio-indigo are dissolved in 700 parts of sul- .phuric acid monohydrate, and 15 parts of bromine are introduced. at or dinary .tem- .pe-rature. QThis mass is .then stirred forabout 1.2 hoursand the product isisolated by adding the brominated mass to about 3000 parts of #ice water. The precipita tionmass is agitated for about one-half hour, filtered'and the filter cake washed with water and pasted. The

atomic weights =ofi-brom-ine.

4. "A. process of reparing brom nated t l dimethvl flW- dichloro thin -indigo corresponding closel in bromine con-tent to the mono-bromo derivative. which comprises treating; approximately 50 parts by weirrht --of 4r l--dimetbvl 6i6 diehloro-thio in disro dissol ed iirsulphuric acid monohvdrate with a pproiii m aftelv 15 parts by-=wei ght of bromine and diluting the solvent mass to precipitate the product. 7

5. As a new article of manutacturea dvestuii cor-Ltainino; brominated AL l dimethvl- 6.6-diehloro-thi o-in digo. the bromine content beinsz substantially less than that of dibromo- 4.4--dimethyl-6.6-clichloro-thioindigo.

6. As anew article of manufactureoa dyestuii' containing bromina-ted 4%F-dimethyL Q5 dyestufliobtamed in 'thiswaycorresponds 6i6 -dichloro-thio-indigo-corresponding close- 1y to the mono-bromo derivative and having most probably the following formula:

CH3 CIHQ 7. Materials dyed with the dyestufi described in claim 5.

8. Materials dyed With the dyestufi de-' scribed in claim 6.

In testimony whereof We have hereunto. subscribed our names. IVAN GUBELMANN.

J. B. OESGH. EMERIC HAVAS. 

